The present invention relates to specific catalysts which are utilized in the hydrogenation of unsaturated hydrocarbon polymers and particularly unsaturated rubber polymers.
Heretofore, various catalysts have been utilized for the hydrogenation of unsaturated polymers such as rubber. However, all of the prior art catalysts are different from reactant compounds of the present invention utilized to make the catalysts. Additionally, some prior art catalysts are difficult and/or expensive to prepare while the catalysts of the present invention are easily and inexpensively formulated.
An early prior art patent, to Breslow, U.S. Pat. No. 3,113,986, relates to the utilization of heavy metal alkoxides or acetylacetonates. U.S. Pat. No. 3,412,174, to Kroll, relates to the reaction product of a transition-metal salt (for example, a cobalt salt of a carboxylic acid), an organometallic (for example, a triisobutyl aluminum) and a Lewis base or weak acids, as a catalyst for hydrogenation. However, the catalysts are ineffective at high temperatures and generally unstable for long periods of time. The patent to LaPorte, U.S. Pat. No. 3,025,278 is substantially identical to that of Kroll.
The patent to Yoshimoto, U.S. Pat. No. 3,531,450, utilizes as a catalyst a nickel compound which must be a carboxylate, chelate or sulfonate and a solvent for preparing the catalysts which must be a chlorinated hydrocarbon or ether. Another Yoshimoto Patent, U.S. Pat. No. 3,625,927, relates to a catalyst wherein a chelating agent is attached to a metal through both a nitrogen atom and an oxygen atom.
Additionally, U.S. Pat. No. 3,868,354 to Halasa, relates to the use of a catalyst which is the reaction product of a cobalt salt of a lactam or other amide or urea reduced by a trialkyl or triaryl aluminum or a dialkyl or diaryl aluminum hydride. Another patent to Halasa, U.S. Pat. No. 3,872,072, relates to a catalyst which is a complex of cobalt chloride and from 1 to 8 molecules of lactam or other amide or urea compound reduced by a trialkyl or triaryl aluminum or a dialkyl or diaryl aluminum hydride. U.S. Pat. No. 3,882,094, also to Halasa, relates to a hydrogenation catalysts which is the reaction product of a complex of pyridine and cobalt chloride, and trialkyl aluminum or dialkyl aluminum hydride.
In contrast, the catalysts of the present invention are different than the prior art, is very effective in hydrogenating unsaturated polymers and is easily and readily prepared.